John C. Chao, DDS

Research Associate Professor, University at Buffalo, SUNY
Adjunct Assistant Professor, Ostrow School of Dentistry, USC

(626) 308-9104

News & Press



John C. Chao, D.D.S., M.A.G.D
Anxiety Management,
Behavior Science,
Faculty, USC School of Dentistry

90% of Cells in the Body Are Not Human
But You Need Them to Maintain Systemic and Dental Health

The vast majority ( approximately 90%) of cells in the human body are not human at all, according to an 2006, article published in Cell, a highly respected peer-review research journal that covers a broad range of disciplines within life sciences. This profound discovery within the field of human biology is explained by the intriguing fact that many of these non-human cells play important roles in normal human physiology. These beneficial germs (microorganism) involved in the absorption of nutrients into the body, synthesis of vitamins and protection of human cells from infection. It may be said that survival of the human body (host) depends on the interaction between human and non-human cells. Therefore it is not entirely correct to say that the human body remains healthy because it fights off bacterial invasion. Actually it may be said that life is maintained by an interdependent, mutually beneficial coexistence between the human and non-human cells.

The human body contains “ecological niches,” such as the oral cavity, to acquire and retain beneficial microorganisms, according to a recent article published this year in Periodontology 2000, highly respected journal in the field of dentistry. The latter article further stated that the oral cavity is a warm, wet and nutrient-rich environment that is ideal for supporting microbial growth. The benefit of having beneficial microorganisms is not without consequences. Undesirable microorganisms continually challenge the delicate biological balance between the human body (host) and beneficial non-human cells. The host deals with the microbial challenge through the release enzymes and immune factors in the saliva and the blood supply. Thus in the healthy individual there exists a dynamic balance that arises out of numerous, complex host-microbial interactions. These interactions called be loosely called “inflammation,” a healing process. However, a substantial disruption of this balance over time can lead to “chronic inflammation.” Chronic inflammation triggers the release of a cascade of self-destructive immune factors, such as white blood cells and enzymes , that may lead to adverse oral conditions, such as periodontitis (gum disease).

Furthermure, chronic inflammation and its associated toxic by-products invariably may also be released into different parts of the body through the circulatory system. Recently research, widely disseminated through the news media, points to the close association between the oral inflammatory processes and systemic disorders, such as diabetes, arthrosclerosis, respiratory diseases, rheumatoid arthritis, Alzheimer’s disease, and certain forms of cancer and even low-weight or pre-term babies.

How does the body facilitate and accommodate beneficial microbes in the oral cavity? Dynamic balance is, by and large, maintained in biofilms, which are initially formed by host cells. This microscopically thin cellular scaffold initially attracts beneficial aerobic microbes that would exist in communal harmony with the host cells.

How does gum disease and cavities develop? Unwelcome anaerobic microbes may invade the biofilms in large numbers under certain conditions, such as inadequate oral hygiene, dry mouth and high sugar intake. The affected biofilms then become “dental plaque,” which leads to cavity formation and periodontal disease. It is also known that internal (endogenous) factors such as stress, external (exogenous) factors such as smoking are associated higher risk of occurrence of gum disease and cavities.

The take-home lesson of understanding of this interesting aspect of oral biology is that oral health stems from a dynamic balance of cells of the human body with oral bacteria and other microbes. Provided the body is generally healthy (not under unusual stress), this biologic balance can be maintained at a healthy level throughout an entire lifetime if healthy habits are followed on a daily basis, with professional care at regular intervals. These healthy habits includes proper brushing, flossing and use of dental aids such as mouthwashes and hydroelectric devices (“water-pik,” “hydrofloss,” etc.). Proper nutrition, stress control, low intake of sugar products are also important in safeguarding this dynamic balance in the mouth. However the patient should understand that since so many factors must be in sync to maintain this dynamic balance, even with the best of homecare there is no guarantee that this dynamic balance would not change. To avoid unpleasant surprises it is therefore recommended that everyone see the dentist regularly for checkups.

An ancillary conclusion to be drawn from this up-to-date concept of biochemistry in the oral cavity is that antibiotics must not be taken indiscriminately. If antibiotics is prescribed, it is only for an particular condition, such as infection causing pain and swelling in the cheeks. Continual use of antibiotics to ameliorate recurrent acute conditions would tend to obliterate beneficial microbes as well as those causing the infection. This results in difficulty in forming a new dynamic balance that leads to more decay and gum infection. In fact, yeast and other opportunistic microorganisms may take over as a result. It is imperative that the offending tooth/teeth be treated or removed and replace. rather than depending on an antibiotic prescription when an infections recurs. Of course it is better to prevent the problem in the first place by following good dental hygiene habits and seeing your dentist regularly for checkups and maintenance.


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